Reflective type liquid crystal display device

ABSTRACT

A liquid crystal display device includes a first substrate, a second substrate, a liquid crystal layer sandwiched between the first and second substrate, plural reflective electrodes arranged on a surface of the first substrate on a liquid crystal layer side thereof, each of the reflective electrodes being adapted to be supplied with a video signal; and plural light-blocking conductive films disposed below the reflective electrodes with an insulating layer interposed between the light-blocking films and the reflective electrodes. Each of the light-blocking films is electrically connected to a corresponding one of the reflective electrodes, and is disposed to cover at least a portion of spacings between the corresponding one of the reflective electrodes and ones of the reflective electrodes adjacent thereto.

BACKGROUND OF THE INVENTION

The present invention relates a liquid crystal display device useful fora liquid crystal projector which illuminates a liquid crystal displayelement with light from a light source and projects images on the liquidcrystal display element on a screen.

Recently, liquid crystal display devices have been widely used insmall-sized display devices, display terminals for office automationequipment and the like. Basically, a liquid crystal display deviceincludes a liquid crystal display panel (also called a liquid crystaldisplay element or a liquid crystal cell) composed of a pair ofinsulating substrates at least one of which is made of a transparentplate, a transparent plastic plate or the like, and a layer of liquidcrystal composition (a liquid crystal layer) sandwiched between theinsulating substrates.

The liquid crystal display devices are divided roughly into thesimple-matrix type and the active matrix type. In the simple-matrix typeliquid crystal display device, a picture element (hereinafter a pixel)is formed by selectively applying voltages to pixel-forming stripelectrodes formed on both of the two insulating substrates of the liquidcrystal display panel, and thereby changing orientation of a portion ofliquid crystal molecules of the liquid crystal composition correspondingto the pixel. On the other hand, in the active-matrix type liquidcrystal display device, the liquid crystal display panel is providedwith signal lines, pixel electrodes, reference voltage electrodes andactive elements each associated with one of the pixel electrodes forpixel selection which are formed on one of the substrates, and a pixelis formed by selecting the active element associated with the pixel andthereby changing orientation of liquid crystal molecules present betweena pixel electrode connected to the active element and the referencevoltage electrode associated with the pixel electrode.

Generally, the active matrix type liquid crystal display device employsthe so-called vertical electric field type in which an electric fieldfor changing orientation of liquid crystal molecules is applied betweenan electrode disposed on one of a pair of opposing substrate and anotherelectrode disposed on the other of the opposing substrates. Also put topractical use is the so-called horizontal electric field type (alsocalled IPS (In-Plane Switching) type) liquid crystal display device inwhich an electric field for changing orientation of liquid crystalmolecules is applied in a direction approximately in parallel with themajor surfaces of the opposing substrates.

Among display devices employing the liquid crystal display device, aliquid crystal projector has been practical use. The liquid crystalprojector illuminates a liquid crystal display element with light from alight source and projects images on the liquid crystal display elementon a screen. Two types, a reflective type and a transmissive type, ofliquid crystal display elements are usable for liquid crystal projector.The reflective type liquid crystal display element is capable of beingconfigured to make approximately the entire pixel area an usefulreflective area, and consequently it has advantages of its small size,high definition display and high luminance over the transmissive typeliquid crystal display element.

Consequently, a small-sized high-definition liquid crystal projector canbe realized by using the reflective liquid crystal display elementwithout decreasing its luminance.

A reflective liquid crystal display element is disclosed in U.S. Pat.No. 5,978,056 issued on Nov. 2, 1999, for example. U.S. Pat. No.5,978,056 discloses a multilayer light blocking film, but does notdisclose the arrangement of two light blocking films spaced from eachother in a direction of their thickness.

SUMMARY OF THE INVENTION

The liquid crystal projector has problems of miniaturization, andincreasing of resolution and luminance. To solve the problems, theliquid crystal display element used for the liquid crystal projectorneeds to be further reduced in size, and further increased in resolutionand luminance. In reducing the size and increasing the resolution andluminance of the transmissive type liquid crystal display element, it isinevitable that the ratio of a light-transmissive area to the entirearea in one pixel (hereinafter the aperture ratio) is reducedconsiderably.

It is an object of the present invention to provide a reflective liquidcrystal display device capable of increasing its luminance, it isanother object of the present invention to provide a reflective liquidcrystal display element featuring a high image quality, and it is stillanother object to provide a liquid crystal display element featuring ahigh image quality by prevention of entering of unwanted light occurringtherein and high light utilization efficiency obtained by a higheraperture ratio, and to provide a liquid crystal projector employing theliquid crystal display element.

In accordance with an embodiment of the present invention, there is aliquid crystal display device comprising: a first substrate; a secondsubstrate; a liquid crystal layer sandwiched between the first substrateand the second substrate; a plurality of reflective electrodes arrangedon a surface of the first substrate on a liquid crystal layer sidethereof, each of the plurality of reflective electrodes being adapted tobe supplied with a video signal; and a plurality of light-blockingconductive films disposed below the plurality of reflective electrodeswith an insulating layer interposed between the plurality oflight-blocking films and the plurality of reflective electrodes, each ofthe plurality of light-blocking films being electrically connected to acorresponding one of the plurality of reflective electrodes, each of theplurality of light-blocking films being disposed to cover at least aportion of spacings between the corresponding one of the plurality ofreflective electrodes and ones of the plurality of reflective electrodesadjacent to the corresponding one of the plurality of reflectiveelectrodes.

In accordance with another embodiment of the present invention, there isa liquid crystal display device comprising: a driving-circuit substrate;a transparent substrate; a liquid crystal layer sandwiched between thedriving-circuit substrate and the transparent substrate; a plurality ofreflective electrodes arranged on a surface of the driving-circuitsubstrate on a liquid crystal layer side thereof; a plurality ofsemiconductor switching elements disposed below the plurality ofreflective electrodes, each of the plurality semiconductor elementsbeing configured to supply a signal to a corresponding one of theplurality of reflective electrodes; a first light-blocking film forcovering the plurality of semiconductor switching elements; and aplurality of second light-blocking films each disposed to cover at leasta portion of spacings between adjacent ones of the plurality ofreflective electrodes.

In accordance with another embodiment of the present invention, there isa liquid crystal display device comprising: a first substrate; a secondsubstrate; spacers made of resin for establishing a spacing between thefirst substrate and the second substrate; a peripheral frame made of theresin and interposed between the first substrate and the secondsubstrate; a liquid crystal component filled in a spaced enclosed by thefirst substrate, the second substrate and the peripheral frame; aplurality of reflective electrodes arranged on a surface of the firstsubstrate on a liquid crystal layer side thereof; a plurality of dummyelectrodes disposed between the plurality of reflective electrodes andthe peripheral frame, each of the plurality of dummy electrodes beingsupplied with a dummy-electrode signal; a plurality of semiconductorswitching elements disposed below the plurality of reflectiveelectrodes, each of the plurality semiconductor elements beingconfigured to supply a signal to a corresponding one of the plurality ofreflective electrodes; a first light-blocking film for covering theplurality of semiconductor switching elements; and a plurality of secondlight-blocking films each disposed to cover at least a portion ofspacings between adjacent ones of the plurality of reflectiveelectrodes.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings, in which like reference numerals designatesimilar components throughout the figures, and in which:

FIG. 1 is a schematic cross-sectional view of a liquid crystal displayelement for explaining an embodiment of the liquid crystal displaydevice in accordance with the present invention;

FIGS. 2A and 2B are illustrations of a liquid crystal display element ofthe electrically controlled birefringence mode for explaining anembodiment of the liquid crystal display device in accordance with thepresent invention;

FIG. 3 is a schematic plan view of a liquid crystal display element forexplaining an embodiment of the liquid crystal display device inaccordance with the present invention;

FIG. 4 is a schematic plan view of a liquid crystal display element forexplaining an embodiment of the liquid crystal display device inaccordance with the present invention;

FIGS. 5A-5C are timing charts for explaining operation of a liquidcrystal display element in an embodiment of the liquid crystal displaydevice in accordance with the present invention;

FIGS. 6A and 6B are schematic equivalent circuits for explainingoperation of a liquid crystal display element in an embodiment of theliquid crystal display device in accordance with the present invention,and FIG. 6C shows a relationship in voltage between electrodes of theliquid crystal display element;

FIG. 7 is a schematic cross-sectional view of a liquid crystal displayelement for explaining an embodiment of the liquid crystal displaydevice in accordance with the present invention;

FIG. 8 is a schematic cross-sectional view of a liquid crystal displayelement for explaining an embodiment of the liquid crystal displaydevice in accordance with the present invention;

FIG. 9 is a schematic cross-sectional view of a liquid crystal displayelement for explaining an embodiment of the liquid crystal displaydevice in accordance with the present invention;

FIG. 10 is a schematic plan view of a liquid crystal display element forexplaining an embodiment of the liquid crystal display device inaccordance with the present invention;

FIG. 11 is a schematic plan view of a liquid crystal display element forexplaining an embodiment of the liquid crystal display device inaccordance with the present invention;

FIG. 12A is a schematic plan view of a terminal portion of a liquidcrystal display element for explaining an embodiment of the liquidcrystal display device in accordance with the present invention, andFIG. 12B is a cross-sectional view of the liquid crystal display elementtaken along line XIIB—XIIB of FIG. 12A;

FIG. 13 is a schematic perspective view of an assembled liquid crystaldisplay element for explaining an embodiment of the liquid crystaldisplay device in accordance with the present invention;

FIG. 14 is a schematic plan view of a liquid crystal display element forexplaining an embodiment of the liquid crystal display device inaccordance with the present invention;

FIG. 15 is an exploded perspective view of an embodiment of the liquidcrystal display device in accordance with the present invention;

FIG. 16 is a schematic plan view of an embodiment of the liquid crystaldisplay device in accordance with the present invention; and

FIG. 17 is a schematic cross-sectional view of the liquid crystaldisplay device of FIG. 16.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The embodiments in accordance with the present invention will now beexplained in detail by reference to the drawings.

FIG. 1 is a schematic cross-sectional view of a liquid crystal displayelement for explaining an embodiment of the liquid crystal displaydevice in accordance with the present invention.

In FIG. 1, reference numeral 100 denotes a liquid crystal displayelement, 1 is a driving circuit substrate, 2 is a transparent substrate,3 is a liquid crystal composition, 4 are spacers. The spacers 4establish a fixed cell gap d between the driving circuit substrate 1 andthe transparent substrate 2 which sandwich the liquid crystalcomposition 3. Reference numeral 5 denotes a reflective electrode formedon the driving circuit substrate 1, 6 is a counter electrode forapplying a voltage across the liquid crystal composition 3 incooperation with the reflective electrode 5, 7 and 8 are orientationfilms for orientating liquid crystal molecules of the liquid crystalcomposition 3 in specified directions, and 30 are active elements forapplying a voltage to the reflective electrode 5.

Reference numeral 34 denote source regions, 35 are drain regions, 36 aregate electrodes, 38 are insulating films, 39 are field oxide films forelectrically insulating transistors from each other, 41 are firstinterlayer insulating films, 42 are first conductive films serving asdrain signal lines, 43 are second interlayer insulating films, 44 arefirst light blocking films, 45 are third interlayer insulating films, 46are second light blocking films, 47 are fourth interlayer insulatingfilms, and 48 are second conductive films forming the reflectiveelectrodes 5.

The conductive film 42 are metal films made of aluminum. The secondinterlayer insulating films 43 insulate the first conductive films 42from the first light blocking films 44. The second interlayer insulatingfilms 43 are composed of planarizing films for flattening stepsgenerated by structures on the driving circuit substrate 1 andinsulating films covering the planarizing films, the planarizing filmsare coated by using a SOG (spin-on-glass) technique and the insulatingfilms are made of SiO₂ formed by a CVD technique using a reactive gas ofTEOS (tetraethylorthosilicate). The second interlayer insulating films43 are planarized by polishing using a CMP (Chemical MechanicalPolishing) technique after deposition of the second interlayerinsulating films 43.

The first light blocking films 44 are formed on the planarized secondinterlayer insulating films 43, and they are made of aluminum like thefirst conductive films 42.

The third interlayer insulating films 45 and the fourth interlayerinsulating films 47 are made of the same material as that of the secondinterlayer insulating films 43, and they are planarized by polishingusing the CMP technique after deposition of the third and fourthinterlayer insulating films 45, 47, respectively.

The second light blocking films 46 and the reflective electrode 5 aremade of aluminum like the first conductive film 42. The third interlayerinsulating films 45 are used as dielectric films for obtainingelectrostatic capacitances as explained subsequently, and theirthickness is preferably in a range of from 150 nm to 450 nm, morepreferably about 300 nm, considering their withstand voltage andincreasing of their electrostatic capacitances by decreasing theirthickness.

First, the reflective type liquid crystal display element will beexplained, and the active element 30 and the first and second lightblocking films 44, 46 will be described subsequently.

The liquid crystal display element in this embodiment is of thereflective type. Light projected into the liquid crystal display element100 enters from the transparent substrate 2 (at the top of FIG. 1), thenpasses through the liquid crystal composition 3, then is reflected backby the reflected electrode 5, then passes through the liquid crystalcomposition 3 again, then passes through the transparent substrate 2,and leaves the liquid crystal display element 100.

In the liquid crystal display element of the reflective type, when thereflective electrode 5 is disposed on the surface of the driving circuitsubstrate 1 on its liquid crystal composition 3 side, an opaquesubstrate such as a silicon substrate can be used as the driving circuitsubstrate 1. This structure has advantages that the active elements 30and wiring can be disposed below the reflective electrodes 5, therebythe area of the reflective electrodes 5 can be increased, andconsequently, the higher aperture ratio can be realized. Also thisstructure has an advantage of radiating heat generated by lightprojected into the liquid crystal display element 100 from the backsurface of the driving circuit substrate 1.

Next, operation of the liquid crystal display element employing theelectrically controlled birefringence mode will be explained. Lightlinearly polarized by a polarizer enters the liquid crystal displayelement 100. When a voltage is applied between the reflective electrode5 and the counter electrode 6, orientation of liquid crystal moleculesof the liquid crystal composition 3 is changed due to their dielectricanisotropy, and as a result the birefringence of the layer of the liquidcrystal composition 3 is changed. The electrically controlledbirefringence mode generates images by converting the changes of thebirefringence into the changes of light transmission.

Next, the single-polarizer twisted nematic (SPTN) mode, which is onetype of the electrically controlled birefringence mode, will beexplained by reference to FIGS. 2A and 2B.

Reference numeral 9 denotes a polarizing beam splitter which divides anincident light L1 from a light source (not shown) into two polarizedlights, and a linearly polarized one L2 of the two.

In FIGS. 2A and 2B, a light having passed through the polarizing beamsplitter 9, which is a p-polarized light, is entered into the liquidcrystal display element 100, but instead a light reflected by thepolarizing beam splitter 9, which is an s-polarized light, can beentered into the liquid crystal display element 100.

The liquid crystal composition 103 is a nematic liquid crystal materialhaving positive dielectric anisotropy. Longitudinal axes of the liquidcrystal molecules are oriented approximately in parallel with the majorsurfaces of the driving circuit substrate 1 and the transparentsubstrate 2 (see FIG. 1), and the liquid crystal molecules are twistedacross the liquid crystal layer by the orientation films 7, 8 (see FIG.1).

FIG. 2A illustrates a case where no voltage is applied across the layerof the liquid crystal composition 3. The light L2 entering the liquidcrystal display element 100 is converted into elliptically polarizedlight by birefringence of the liquid crystal composition 3, and thenbecomes approximately circularly polarized light on the reflectiveelectrode 5. The light reflected by the reflective electrode 5 passesthrough the liquid crystal composition 3 again, thereby becomeselliptically polarized light again, and then returns to linearlypolarized light again when it leaves the liquid crystal display element100. The emergent linearly polarized light L3 is s-polarized lighthaving its direction of polarization rotated through an angle of 90°with respect to that of the incident light L2, enters the polarizingbeam splitter 9 again, and then is reflected by an internal interface ofthe polarizing beam splitter 9 to become emergent light L4 which in turnis projected onto a screen or the like to produce a display. Thisconfiguration is of the so-called normally white (normally open) typewhich emits light when a voltage is not applied across the layer of theliquid crystal composition 3.

FIG. 2B illustrates a case where a voltage is applied across the layerof the liquid crystal composition 3. When an electric field is appliedacross the layer of the liquid crystal composition 103, the liquidcrystal molecules align in a direction of the electric field andconsequently, the birefringence of the liquid crystal molecules does notappear. As a result, the linearly polarized light L2 entering the liquidcrystal display element 100 is reflected by the reflective electrode 5without undergoing changes, and then the light L5 emergent from theliquid crystal display element 100 has the same direction ofpolarization as that of the incident light L2. The emergent light L5passes through the polarizing beam splitter 9, and returns to the lightsource such that no light is projected onto the screen and a blackdisplay is provided on the screen.

In the single-polarizer twisted nematic mode, the direction oforientation of the liquid crystal molecules is parallel with the majorsurfaces of the substrates, and therefore usual methods of orientatingthe liquid crystal molecules can be employed and its manufacturingprocess is highly stable. The normally white mode operation ispreventive of defective displays occurring at low voltage levels. Thereason is that, in the normally white mode, a dark level (a blackdisplay) is provided when a high voltage is applied across the liquidcrystal layer, and in this state, almost all the liquid crystalmolecules are orientated in the direction of the electric field which isperpendicular to the major surfaces of the substrates, and consequently,a display of the dark level does not depend very much upon the initialconditions of orientation of the liquid crystal molecules having a lowelectric field applied thereto.

The human eye perceives non-uniformity in luminance based upon the ratioof luminances, is responsive approximately to the logarithm ofluminance, and consequently, is sensitive to variations in dark levels.

Because of the above reasons, the normally white mode has advantageswith respect to prevention of non-uniformity in luminance caused byinitial conditions of orientation of the liquid crystal molecules.

The electrically controlled birefringence mode requires a highly precisecell gap between the substrates of the liquid crystal display element.The electrically controlled birefringence mode utilizes a phasedifference between ordinary rays and extraordinary rays caused whilethey pass through the liquid crystal layer, and therefore the intensityof the light transmission through the liquid crystal layer depends uponthe retardation Δn·d between the ordinary and extraordinary rays, whereΔn is a birefringence and d is a cell gap established by spacers 4between the transparent substrate 2 and the driving circuit substrate 1(see FIG. 1).

In the reflective type liquid crystal display element, light enteringthe liquid crystal layer is reflected by the reflective electrode, andthen passes through the liquid crystal layer again, therefore, if thereflective type liquid crystal display element uses a liquid crystalcomposition having the same birefringence Δn as that of a liquid crystalcomposition used in the transmissive type liquid crystal displayelement, the cell gap d of the reflective type liquid crystal displayelement needs to be half that of the transmissive type liquid crystaldisplay element. Generally, the cell gap d of the transmissive liquidcrystal display element is in a range of about 5 microns to about 6microns, and in this embodiment the cell gap d is selected to be about 2microns.

In this embodiment, to ensure a high accuracy of the cell gap and asmaller cell gap than that of conventional liquid crystal displayelements, column-like spacers are fabricated on the driving circuitsubstrate 1 instead of using a bead-dispersing method.

FIG. 3 is a schematic plan view of a liquid crystal display element forexplaining an arrangement of the reflective electrodes 5 and the spacers4 disposed on the driving circuit substrate 1. A large number of spacers4 are arranged in a matrix array over the entire area of the drivingcircuit substrate 1 for establishing a uniform spacing between thetransparent substrate 2 and the driving circuit substrate 1. Each of thereflective electrodes 5 defines a pixel serving as the smallest pictureelement formed by the liquid crystal display element. For the sake ofsimplicity, FIG. 3 illustrates an array of five columns by four rows ofpixels, pixels in the outermost columns and rows are represented byreference numeral 5B, pixels within the outermost columns and rows arerepresented by reference numeral 5A.

In FIG. 3, the array of five columns by four rows of pixels forms adisplay area, in which a display by the liquid crystal display elementis formed. Dummy pixels 10 are disposed around the display area, aperipheral frame 11 made of the same material as that of the spacers 4is disposed around the dummy pixels 10, and a sealing member 12 iscoated around the peripheral frame 11 on the driving circuit substrate1. Reference numeral 13 denotes terminals for external connections whichare used for supplying external signals to the liquid crystal displayelement 100.

The spacers 4 and the peripheral frame 11 are formed of resin material.The liquid crystal composition 3 is placed between the driving circuitsubstrate 1 and the transparent substrate 2, and then is confined withina region enclosed by the peripheral frame 11 after the liquid crystaldisplay element 100 has been assembled (see FIG. 1). A sealing member 12is coated around the peripheral frame 11 on the driving circuitsubstrate 101 to seal the liquid crystal composition 3 off in the liquidcrystal display element 100. The spacers 4 and the peripheral frame canbe made of a resin material such as a chemically amplified negativephotoresist “BPR-113” (a trade name) manufactured by JSR Corp. (Tokyo,Japan). The photoresist material is coated as by a spin coating methodon the driving circuit substrate 1 having the reflective electrodes 5formed thereon, then is exposed through a mask having a pattern in theform of the spacers 4 and the peripheral frame 11, and then is developedby a remover to form the spacers 4 and the peripheral frame 11.

The sealing member 12 serves to fix the driving circuit substrate 1 andthe transparent substrate 2 together, and also serves to preventmaterials harmful to the liquid crystal composition 3 from penetratingthereinto. When the fluid sealing member 12 is applied, the peripheralframe 11 serves as a stopper against the sealing member 12. Provision ofthe peripheral frame 11 serving as the stopper against the sealingmember 12 makes possible it to define the border of the area of theliquid crystal composition 3 and that of the sealing member 12accurately, and thereby to minimize the necessary inactive regions suchas dummy pixels and a sealing region which do not contribute togeneration of a display and to reduce the size of the liquid crystaldisplay element. This structure provides a wide latitude in design andthereby makes possible reduction of the region between the display areaand the peripheral sides of the liquid crystal display element 100, thatis, the reduction of the peripheral border around the display area.

The dummy pixels are disposed between the peripheral frame 11 and thedisplay area for making the quality of the display produced by theoutermost pixels 5B equal to that of the display produced by the pixels5A disposed inside the outermost pixels 5B. The dummy pixels which donot contribute to production of a display, but is similar in structureto that of the pixels in the display area is provided at the peripheralareas surrounding the display area so as to prevent defective displayscaused by structural discontinuity at the border between the displayarea and the peripheral areas surrounding the display area.

The dummy pixels are also intended to prevent occurrence of defectivedisplays in the so-called dot-inversion drive in which adjacent pixelshave applied thereto driving voltages of the opposite polarities fromeach other, and the polarities are inverted periodically.

The pixels 5A disposed inside the outermost pixels 5B will behereinafter referred to as the inner pixels 5A. By referring to FIG. 4,the purpose of the dummy pixels will be explained. The inner pixels 5Ahave pixels adjacent to each other, and therefore unwanted electricfields are generated between adjacent of the inner pixels 5A when thecolumn-inversion, line-inversion or dot-inversion driving method isemployed. On the other hand, the above-mentioned unwanted electricfields which deteriorate display quality are not generated between theoutermost pixels 5B and the areas on the side opposite from the innerpixels 5A when the dummy pixels 10 are not provided, and consequently,the outermost pixels 5B provides a display better in quality than thatprovided by the inner pixels 5A. A difference in display quality betweensome of the pixels produces non-uniformity in display. Therefore, thedummy electrodes 10 are provided to the liquid crystal display elementsdriven the dot-inversion drive method, and are supplied with signalslike the pixels 5A, 5B such that display quality provided by theoutermost pixels 5B are made equal to that provided by the inner pixels5A.

In the present embodiment, the column-inversion, line-inversion ordot-inversion driving method is not employed, and therefore a problem ofnon-uniformity in display does not arise which occurs in thecolumn-inversion, line-inversion or dot-inversion driving. However, whenthe liquid crystal display element of the present embodiment is drivenin the normally white mode, a problem arises in that the dummy pixels 10appear and degrade display quality if no voltage is applied across thelayer of the liquid crystal composition 3. It is conceivable to shieldthe dummy pixels 10 from light by using a light blocking border, but itis difficult to position the light blocking border accurately at theborder of the display area. In view of this, the dummy pixels 10 aresupplied with such a voltage to make them produce a black display suchthat they are observed as a black border surrounding the display area.The width of the dummy pixels 10 disposed inside the peripheral frame 11are selected to be equivalent to two or more lines of the regularpixels.

FIG. 4 illustrates the dummy pixel 10D fabricated in the form of aperipheral frame, and the dummy pixel 10D is supplied with such avoltage to make it produce a black display. When the dummy pixel 10 isshaped as a single electrode in the form of a peripheral frame as shownin FIG. 4, a black display in the form of the peripheral frame iscomparatively easily realized around the display area.

However, it was found out that the dummy pixel 10 shown in FIG. 4produces a defective display at the border between the dummy pixel 10and the display area.

When an electric field is applied across the layer of the liquid crystalcomposition 3 in a fixed direction for a long period of time, the liquidcrystal composition 3 is deteriorated, and in view of this phenomenon, aso-called AC driving method is known which inverts the polarities of theelectric field applied across the layer of the liquid crystalcomposition 3 periodically. In this embodiment, the frame-inversiondrive method is employed which inverts the polarities of signals at allthe pixels once per frame time, that is, with twice the frame time.

In the frame-inversion drive method, signals of the same polarity arewritten into respective ones of the pixels for one frame time. In FIG.4, writing of signals into the effective pixels in the display area isperformed in the scanning order from the top row to the bottom row, andon the other hand, writing of a signal into the dummy pixel 10D isperformed at one time because the dummy pixel 10D is in the form of asingle electrode. As a result, some of the effective pixels have appliedthereto signals of the polarity opposite from that of the signal appliedto the dummy pixel 10D for a portion of the period depending upon a timeof the period they are scanned, and consequently, effective lateralelectric fields between the dummy pixels 10D and effective pixelsadjacent thereto become non-uniform depending upon positions of theeffective pixels. A typical example of this phenomenon will now beexplained by using a case of producing a black display over the entiredisplay area.

In FIG. 4, a black-displaying signal (a high voltage if in the case ofthe normally white mode) is written into the respective effective pixelsat positions from the upper left-hand corner to the lower right-handcorner of the display area sequentially within one frame time. If theblack-displaying signal is written into the dummy pixel 10D at the sametime the black-displaying signal is written into the effective pixel atthe upper left-hand corner with both the black-displaying signals to thedummy pixel 10D and the effective pixels having the same polarity, alateral electric field is generated between the effective pixel at thelower right-hand corner of the display area and the dummy pixel 10Dduring approximately the entire frame time, and lateral electric fieldsare generated between the outermost effective pixels and the dummy pixel10D for a length of a time difference between times of writing thesignals into the outermost effective pixels and the dummy pixel 10D. Inthe normally white mode, an unwanted lateral electric field produced bythe black-displaying signal generates a locally white portion in a blackbackground, that is, if a black display is intended over the entiredisplay area, a white peripheral frame appears between the display areaand the dummy pixel and the brightness of the peripheral frame variesfrom place to place.

FIGS. 5A-5C illustrate timing charts of video signals in theframe-inversion driving, and differences in writing time will beexplained by reference to FIGS. 5A-5C. A signal SE in FIG. 5B representsa video signal which is written into and stored in the pixels 5E in thefirst row in FIG. 4, a signal SF in FIG. 5C represent a video signalsupplied to the pixels 5F in the fourth line, a signal SD represents ablack-displaying signal supplied to the dummy pixel 10D, and Vcom inFIGS. 5A-5C represent a voltage applied to the counter electrode 6 (seeFIG. 1).

To facilitate understanding, FIGS. 5A-5C illustrates a case in which ablack-displaying signal is applied to all the pixels (an all-blackdisplay). The order of writing of video signals into the pixelssequentially is from the upper left-hand corner to the lower right-handcorner of the display area in the example shown in FIG. 4, andtherefore, first the black-displaying signals are written into thepixels in the first row sequentially, and then the black-displayingvideo signals are written in the pixels in the second row to the fourthrow sequentially in the same way as in the first row. On the other hand,writing of the black-displaying signal into the dummy pixel 10D isperformed simultaneously with writing of the signal into the pixels 5Ein the first row. The polarity of the video signals in the first frameis positive with respect to the voltage Vcom, and the polarity of thevideo signals in the second frame is negative with respect to thevoltage Vcom.

In FIGS. 5A-5C, the video signal SE is written in the pixels 5E at atime indicated by an arrow AE1, and then is held in the pixels 5E untila time indicated by an arrow AE2. The video signals are written into thepixels line by line from the top row to the bottom row, and thereforethe video signals SF are written into the pixels 5F in the fourth row ata time indicated by an arrow AF1. The phase of the video signal SFwritten into the pixels 5F lags that of the black-displaying signal SDwritten into the dummy pixel 10D by approximately one frame time. As aresult the black-displaying signal SD and the video signal SF areopposite in polarity from each other for approximately one frame time,and therefore unwanted electric fields are generated between the pixels5F and the dummy pixels 10D. The unwanted electric fields changeorientation of molecules of the liquid crystal composition 3 such thatlocally somewhat white portions appear in a black display in thenormally white mode, resulting in non-uniform display.

The above explanation have been made by referring to the pixels 5F inthe fourth row, but the pixels in the second and third rows areimpressed with the voltages opposite in polarity with respect to thevoltage applied to the dummy pixel 10D, and consequently, similarnon-uniformity in display are produced by the pixels in the second andthird rows, but the degree of the non-uniformity varies depending uponthe length of time for which the respective pixels are impressed withthe voltages opposite in polarity with respect to the voltage applied tothe dummy pixel 10D.

Returning to FIG. 3 again, the embodiment of the present invention willbe explained further. To prevent occurrence of non-uniformity caused bythe structure of the dummy pixel 10D explained in connection with FIG.4, the present embodiment employs a structure in which a plurality ofdummy pixels are provided such that dummy pixels in adjacent rows areseparated from each other as shown in FIG. 3. The black-displayingsignal is written into each of the dummy pixels 10 simultaneously withwriting of signals into the effective pixels in a corresponding row.That is to say, each of the dummy pixels 10 provided for each row of theeffective pixels receives a signal of the same polarity as that of asignal written into the pixels of a corresponding row, and consequently,occurrence of the unwanted electric fields can be prevented andnon-uniformity in display can be reduced.

Further, the dummy pixels 10 shown in FIG. 3 are laterally elongatedcompared with the effective pixels 5A and 5B. The liquid crystal displayelement 100 is provided with a light blocking frame for blockingunwanted light from illuminating portions other than the display area asdescribed subsequently. Lateral elongation of the dummy pixels 10provides a larger tolerance to positioning accuracy of the lightblocking frame in the liquid crystal display element 100.

The following explains a method for varying a voltage of the reflectiveelectrode 5 with respect to the counter electrode 6 by application of avoltage to the first light blocking film 44 by using a capacitor formedbetween the first and second light blocking films 44, 46 in thestructure shown in FIG. 1, by reference to FIGS. 6A-6C. An equivalentcircuit for one pixel is illustrated in FIGS. 6A and 6B in which theactive element 30 is represented by a switch for clarity. Referencenumeral 52 denotes a scanning signal line for supplying signals to turnthe active element 30 ON or OFF, and 51 is a video signal line forsupplying a video signal to be written into the pixel. As shown in FIGS.6A and 6B, the reflective electrode 5 and the counter electrode 6 form afirst capacitor 53, and the first light blocking film 44 and the secondlight blocking film 46 form a second capacitor 54. For simplicity, otherparasitic capacitances are neglected, and the capacitances of the firstcapacitor 53 and the second capacitor 54 are denoted by CL and CC,respectively.

As shown in FIGS. 6A and 6C, the first light blocking film 44 serving asone electrode of the second capacitor 54 is supplied with a voltage V1from some external source. When the active element 30 is turned ON by ascanning signal, a video signal V2 is supplied to the reflectiveelectrode 5 and the second light blocking film 46.

Then, as shown in FIGS. 6B and 6C, at a time the active element 30 isturned OFF, the voltage applied to the first light blocking film 44 ischanged from the voltage V1 to a voltage V3. As a result the voltage ofthe reflective electrode 5 and the second light blocking film 46 becomesV2−CC/(CL+CC)×(V1−V3).

By using the above-explained method for varying the voltage of thereflective electrode 5, a voltage of negative polarity is produced by avoltage applied to the first light blocking film 44 with the reflectiveelectrode 5 being supplied with a voltage of positive polarity, forexample. This method for producing a voltage of negative polarityeliminates the need for supplying a voltage of negative polarity, andthe peripheral circuit which have conventionally supplied signals ofboth positive and negative polarities can be configured to supply signalof only one of positive and negative polarities, making possible alow-voltage peripheral circuit and thereby making possible formation ofthe peripheral circuit by using low-voltage rating components.

Next, the first and second light blocking films 44, 46 will be explainedby reference to FIGS. 7-10.

As shown in FIG. 7, the reflective electrodes 5 are spaced from eachother with a specified gap therebetween to define the respective pixels.Light passes through the gaps, then enters a semiconductor layer of theactive element 30, and generates charges (photocarriers) byphotoelectric conversion. A portion of the photocarriers flow into thesource region, change the video signal having been written into andstored in the reflective electrodes 5, and this is the so-calledphotoleak problem.

When the intensity of light from the light source is small, a largeportion of the light is reflected by the reflective electrodes 5 whichhave functions of reflect light and shielding circuits underlying thereflective electrodes 5 from light, and consequently, light passingthrough the gaps does not cause a problem.

However, in the liquid crystal projector, strong light from the lightsource illuminates the liquid crystal display element 100 to increaseluminance of the liquid crystal projector. Also there is a tendency thatthe display area of the liquid crystal display element decreases withdecreasing size of the liquid crystal display element as the size of theliquid crystal projector is reduced, and as a result the illuminationintensity on the display area of the liquid crystal display element isreduced further. Consequently, the photoleak cannot be prevented by thereflective electrodes 5(48) and therefore the light blocking films needto employed.

When color filters 21 are disposed on the transparent substrate 2 asshown in FIG. 7, a black matrix 20 made of light blocking films can beformed between the color filters 21. The black matrix 20 is formed so asto surround each of the pixels and this means the black matrix 20 ispatterned to block light from illuminating the gaps between thereflective electrodes 5(48). Therefore the black matrix 20 suffices forlight blocking in the conventional liquid crystal display elements. Butthe transparent substrate 2 is spaced from the driving circuit substrate1, and consequently, the photoleak caused by light entering obliquelycannot be neglected when the intensity of the incident light isincreased.

Among the liquid crystal projector, there is a type in which colorsplitting and recombination are performed outside the liquid crystaldisplay element, and this type of liquid crystal display elements do notincorporate color filters thereinto, and therefore it is not economicalin view of manufacturing steps to fabricate the black matrix 20 on thetransparent substrate 2 for the purpose of light blocking only. Further,employment of the black matrix 20 in the reflective liquid crystaldisplay element causes a problem of reducing the aperture ratio.

As a solution to the above problems, in this embodiment of the presentinvention, light blocking films are formed on the driving circuitsubstrate 1 by using process steps similar to those for fabrication ofother metal layers in the liquid crystal display element. FIG. 8illustrates the structure in which the light blocking films 44 arefabricated on the driving circuit substrate 1. The light blocking films44 can be disposed closely to the semiconductor layer and block theobliquely incident light. Each of the light blocking films 44 can coverthe entire area of a corresponding pixel, an opening to be made in thelight blocking film 44 is only a contact hole 42CH for electricalconnection to the reflective electrode 5, and the amount of lightincident on the semiconductor layer is reduced to be very small.

As described above, the liquid crystal projectors have made muchprogress in increasing its luminance, there is a demand for liquidcrystal projectors for use even under normal room lighting condition,and therefore the amount of light illuminating the liquid crystaldisplay element from a light source has been increased.

The present inventors found out that flicker occurs in display due tothe leakage of light caused by the increased amount of light even in thestructure of FIG. 8. It is conceivable to prevent a problem of lightleakage by reducing the size of the openings in the first light blockingfilms 44 and thereby decreasing the amount of light incident on thesemiconductor layer, but in this embodiment second light blocking filmsare disposed below the openings in the reflective electrodes 5 as analternative.

The first and second light blocking films 44, 46 are disposed in theembodiments shown in FIGS. 1 and 9. In FIG. 9, a connecting portionbetween the second light blocking film 46 and the first conductive film42 has a structure in which a metal film forming the second lightblocking film 46 and a metal film 44B made of the same metal as thefirst light blocking film 44 are laminated, but the second lightblocking metal film 46 may be connected directly to the first conductivefilm 42.

FIG. 10 is a schematic plan view of the arrangement of the reflectiveelectrodes 5 and the second light blocking films 46 viewed from theliquid crystal layer side with the orientation film being omitted forclarity. As shown in FIG. 10, the second light blocking films 46 aredisposed below the reflective electrodes 5 viewed from the liquidcrystal layer side, light passes only through exposed portions 49covered by none of the reflective electrodes 5 and the second lightblocking films 46, and consequently, the amount of light incident on thesemiconductor layer through the openings in the reflective electrodes 5is greatly reduced. The size of the respective second light blockingfilms 46 is made approximately equal to that of the respectivereflective electrodes 5, and therefore the second light blocking films46, are capable of covering most of the area of the openings 5P in thereflective electrodes 5P. As a dimensional example of an individualreflective electrode 5, one reflective electrode 5 is about 8 microns inheight and about 8 microns in width, and a gap between the adjacentreflective electrodes 5 is 0.5 microns.

Each of the reflective electrodes 5 is supplied with a video signalassociated with a corresponding one of the pixels independently ofothers of the reflective electrodes 5 associated with others of thepixels, and therefore the adjacent reflective electrodes 5 are separatedfrom each other by openings 5P for electrical isolation. Each of thesecond light blocking films 46 is also supplied with a video signalassociated with a corresponding one of the pixels independently ofothers of the second light blocking films 46, like the reflectiveelectrodes 5, and therefore the adjacent second light blocking films 46are separated from each other by openings 46P.

Light can pass through the openings 5P and 46P provided for electricalisolation. The openings 5P in the reflective electrodes 5 are blocked upby the second light blocking film 46 so that light does not enter thesemiconductor layer directly, and the openings 46P in the second lightblocking films 46 are blocked up by the reflective electrodes 5 so thatlight does not enter the openings 46 directly. In this way the openingsin one of the reflective electrodes 5 and the second light blockingfilms 46 are blocked up by the other of the reflective electrodes 5 andthe second light blocking films 46 so as to enhance the light blockingeffect.

However, the openings 5P are not blocked up by the direct contact of thesecond light blocking films 46 with the openings 5P. The interlayerinsulating film 47 is disposed between the reflective electrodes 5 andthe second light blocking films 46 so as to insulate them from eachother, and consequently, light can propagate in the interlayerinsulating film 47. In view of this, the first light blocking films 44are provided to further prevent light from entering the semiconductorlayer. Light can enter the semiconductor layer only through the openings49, and therefore the amount of light incident on the semiconductorlayer is limited, but provision of the first light blocking films 44 canprevent light more securely from entering the semiconductor layer. Anopening to be formed in each of the first light blocking films 44 is acontact hole 42CH for provided for each of the pixels. The first lightblocking films 44 further block up the openings 49 causing light leakagewhich cannot be eliminated even by provision of the second lightblocking film 46.

As shown in FIG. 11, the openings 49 causing light leakage can beblocked up directly by insulating materials. For example, light blockingfilms can be formed on the light leakage openings 49 by using the sameresin material as that of the spacers 4. In FIG. 11, the spacers 4 aredisposed on the openings 49. Further, the openings 5P in the reflectiveelectrodes 5 can be blocked up by light blocking resin films.

As described already, capacitors can be formed between the first andsecond light blocking films 44, 46. The second light blocking films 46are supplied with the same video signals as those written into thereflective electrodes 5, and therefore the capacitors can be used as thestorage capacitances when a fixed voltage is applied to the first lightblocking films 44. The second light blocking films 46 which are suppliedwith video signals function as second reflective electrodes also. Asshown in FIG. 10, the second light blocking films 46 are exposed in theopenings 5P between the adjacent reflective electrodes 5, and thereforethe second light blocking films 46 can apply an electric field to theliquid crystal composition 3 via the fourth interlayer insulating film47 and the orientation film 7 (see FIG. 1). The second light blockingfilms 46 are AC-driven in the same manner as the reflective electrodes 5are, and therefore the liquid crystal composition 3 in the vicinity ofthe openings 5P can be impressed with voltages whose polarity isinverted periodically, by the second light blocking films 46, andconsequently, application of electric fields in a fixed direction, i.e.,DC fields, to the liquid crystal composition 3 in the vicinity of theopenings 5P is prevented.

Next, a dummy pattern formed for making uniform a pattern density withina chip will be explained by reference to FIGS. 12A and 12B. FIGS. 12Aand 12B illustrate a dummy pattern 14 formed around the externalterminals 13. There are no structures other than the external terminals13 disposed between the adjacent external terminals on the drivingcircuit substrate 1 for prevention of electrical shorts in connectingthe external terminals to an external circuit, and consequently, thepattern density of the area where the external terminals 13 are disposedis usually lower than that of the remainder of the driving circuitsubstrate 1. In chemical mechanical polishing, the amount of polishingdepends upon the density of uneven structures (the pattern density) ofthe surface to be polished, and the flatness of the polished surface isdegraded due to the unevenness. By disposing the dummy pattern 14 in aarea around the external terminals 13 where the pattern density is low,the pattern density of the area around the external terminals is madeuniform, and consequently, the subsequent chemical mechanical polishingmakes possible a thin film having a uniformly flat surface.

FIG. 12B is a cross-sectional view of the driving circuit substrate 1taken along line XIIB—XIIB of FIG. 12A. The external terminal 13 iscomprised of superposed layers of the first conductive film 42, thefirst light blocking film 44, the second light blocking film 46 and thereflective electrode 5. To increase the thickness of a conductive filmin the connecting portion, the conductive film in the connecting portionis composed of the three superposed layers of the first light blockingfilm 44, the second light blocking film 46 and the reflective electrode5. The signal lines disposed within the driving circuits are made of thefirst conductive film 42, and therefore the first light blocking film 44and the first conductive film 42 are connected together via a contacthole made in the interlayer insulating film.

FIG. 13 is a perspective view of the driving circuit substrate 1superposed with the transparent substrate 2. Formed at the periphery ofthe driving circuit substrate 1 is the peripheral frame 11, and theliquid crystal composition 103 is confined in a space surrounded by theperipheral frame 11, the driving circuit substrate 1 and the transparentsubstrate 2. The sealing member 12 is coated around the outside of theperipheral frame 11 between the superposed driving circuit substrate 1and transparent substrate 2. The driving circuit substrate 1 and thetransparent substrate 2 are fixed together by the sealing member 2 toform the liquid crystal display element (the liquid crystal displaypanel) 100.

Next, as shown in FIG. 14, connected to the external terminals 13 is aflexible printed wiring board 80 for supplying external signals to theliquid crystal display element 100. Two outermost terminals on one endof the flexible printed wiring board 80 are made longer than theremainder of terminals to form counter-electrode terminals 81 to beconnected to the counter electrode 6 formed on the transparent substrate2. In this way, the flexible printed wiring board 80 is connected toboth of the driving circuit substrate 1 and the transparent substrate 2.

Conventionally, a flexible printed wiring board is connected to externalterminals disposed on the driving circuit substrate 1, and therefore thewiring to the counter electrode 6 from the flexible printed wiring boardis made via the driving circuit substrate 1.

The transparent substrate 2 in this embodiment of the present inventionis provided with connecting portions 82 to be connected to the flexibleprinted wiring board 80 such that the flexible printed wiring board 80is connected directly to the counter electrode 6. The liquid crystaldisplay panel 100 is formed by superposing the transparent substrate 102on the driving circuit substrate 101. The transparent substrate 2 issuperposed on the driving circuit substrate 1 such that a peripheralportion of the transparent substrate 2 extends beyond the outside edgesof the driving circuit substrate 1 and provides the connecting portions82 where the flexible printed wiring board 80 is connected to thecounter electrode 6.

FIGS. 15, 16 and 17 illustrate a configuration of the liquid crystaldisplay device 200. FIG. 15 is an exploded view in perspective of themajor elements of the liquid crystal display device 200, FIG. 16 is aplan view of the liquid crystal display device 200, and FIG. 17 is across-sectional view of the liquid crystal display device of FIG. 16. InFIG. 17, thickness of the respective components is exaggerated forclarity.

As shown in FIG. 15, the liquid crystal display panel 100 having theflexible printed wiring board 80 connected thereto is disposed on theheat-radiating plate 62 with a cushion member 61 interposedtherebetween. The cushion member 61 is highly heat-conductive, and fillsa gap between the heat-radiating plate 62 and the liquid crystal displaypanel 100 for heat from the liquid crystal display panel 100 to conductto the heat-radiating plate 62 easily. Reference numeral 63 denotes amold case, which is fixed to the heat-radiating plate 62 with anadhesive.

As shown in FIG. 17, the flexible printed wiring board 80 is passedbetween the mold case 63 and the heat-radiating plate 62, and then isbrought out of the mold case 63. Reference numeral 65 denotes alight-blocking plate which prevents light from a light source fromentering the unintended portions of the liquid crystal display device200, and 66 is a light-blocking frame which is made of a glass plate anddefines the display area of the liquid crystal display device 200.

As explained above, the present invention is capable of realizing areflective type liquid crystal display device useful for the liquidcrystal projector expected to reduce its size, and increase itsresolution and luminance. Further, the present invention realizes ahigh-display quality reflective type liquid crystal display device, andthe present invention realizes a high-display quality liquid crystaldisplay device and a liquid crystal projector employing it by preventingunwanted incident light from occurring in the liquid crystal displayelement.

What is claimed is:
 1. A liquid crystal display device comprising: afirst substrate; a second substrate; a liquid crystal layer sandwichedbetween said first substrate and said second substrate; a plurality ofreflective electrodes arranged on a surface of said first substrate on aliquid crystal layer side thereof, each of said plurality of reflectiveelectrodes being adapted to be supplied with a video signal; a counterelectrode disposed on a surface of said second substrate on a liquidcrystal layer side thereof: a plurality of second light-blockingconductive films disposed below said plurality of reflective electrodeswith an insulating layer interposed between said plurality of secondlight-blocking films and said plurality of reflective electrodes; and afirst light-blocking film disposed below said plurality of secondlight-blocking conductive films and formed to cover spacing between saidplurality of second light-blocking conductive films; each of saidplurality of second light-blocking films being electrically connected toa corresponding one of said plurality of reflective electrodes, each ofsaid plurality of second light-blocking films being disposed to cover atleast a portion of spacings between said corresponding one of saidplurality of reflective electrodes and ones of said plurality ofreflective electrodes adjacent to said corresponding one of saidplurality of reflective electrodes. wherein each of said plurality ofsecond light-blocking films forms a capacitance with said firstlight-blocking film, and a polarity of a voltage supplied to each ofsaid plurality of second light-blocking conductive films is invertedwith respect to a voltage applied on said counter electrode at specifiedtime intervals.
 2. A liquid crystal display device comprising: adriving-circuit substrate; a transparent substrate; a liquid crystallayer sandwiched between said driving-circuit substrate and saidtransparent substrate; a plurality of reflective electrodes arranged ona surface of said driving-circuit substrate on a liquid crystal layerside thereof; a counter electrode disposed on a surface of saidtransparent substrate on a liquid crystal layer side thereof; aplurality of semiconductor switching elements disposed below saidplurality of reflective electrodes, each of said plurality ofsemiconductor switching elements being configured to supply a videosignal to a corresponding one of said plurality of reflectiveelectrodes; a first light-blocking film for covering said plurality ofsemiconductor switching elements; and a plurality of secondlight-blocking films each disposed to cover at least a portion ofspacings between adjacent ones of said plurality of reflectiveelectrodes, each of said plurality of second light-blocking films beingelectrically connected to a corresponding one of said plurality ofreflective electrodes, wherein each of said plurality of secondlight-blocking films forms a capacitance with said first light-blockingfilm, and a polarity of said video signal supplied to each of saidplurality of reflective electrodes is inverter with respect to a voltageapplied on said counter electrode by varying a voltage supplied to saidfirst light-blocking film.
 3. A liquid crystal display devicecomprising: a first substrate; a second substrate; spacers made of resinfor establishing a spacing between said first substrate and said secondsubstrate; a peripheral frame made of said resin and interposed betweensaid first substrate and said second substrate; a liquid crystalcomponent filled in a space enclosed by said first substrate, saidsecond substrate and said peripheral frame; a plurality of reflectiveelectrodes arranged on a surface of said first substrate on a liquidcrystal layer side thereof; a counter electrode disposed on a surface ofsaid second substrate on a liquid crystal layer side thereof; aplurality of dummy electrodes disposed between said plurality ofreflective electrodes and said peripheral frame, each of said pluralityof dummy electrodes being supplied with a dummy-electrode signal; aplurality of semiconductor switching elements disposed below saidplurality of reflective electrodes, each of said plurality ofsemiconductor switching elements being configured to supply a videosignal to a corresponding one of said plurality of reflectiveelectrodes; a first light-blocking film for covering said plurality ofsemiconductor switching elements; and a plurality of secondlight-blocking conductive films each disposed to cover at least aportion of spacings between adjacent ones of said plurality ofreflective electrodes. wherein each of said plurality of secondlight-blocking films forms a capacitance with said first light-blockingfilm, and a polarity of said video signal supplied to each of saidplurality of second light-blocking conductive films is inverted withrespect to a voltage applied on said counter electrode at specified timeintervals.
 4. A liquid crystal display device according to claim 3,wherein said dummy-electrode signal is such that said dummy electrodes,disposed between said plurality of reflective electrodes and saidperipheral frame, provide a black display.
 5. A liquid crystal displaydevice according to claim 3, wherein a polarity of said dummy-electrodesignal applied to one of said plurality of dummy electrodes is reversedin synchronism with a said video signal applied to one of said pluralityof reflective electrodes adjacent to said one of said plurality of dummyelectrodes.